What is the recommended dose of naloxone (Narcan) for a morphine overdose?

Naloxone Dosing for Morphine Overdose

For morphine overdose with respiratory depression or severe opioid toxicity, administer naloxone 0.4-2.0 mg IV initially, repeating every 2-5 minutes as needed to restore adequate ventilation without precipitating severe withdrawal. 1

Initial Dosing Strategy

The recommended approach depends on the clinical context and patient opioid tolerance:

For Opioid-Naïve or Unknown Tolerance Patients

• Start with 0.1 mg/kg IV/IM (maximum 2 mg for patients ≥20 kg or ≥5 years old) 1
• For adults, this translates to 0.4-2.0 mg IV as the initial dose 1
• Repeat doses every 2 minutes until respiratory function improves 1

For Opioid-Tolerant Patients or Therapeutic Overdose

• Use lower initial doses (0.01-0.015 mg/kg or 1-15 mcg/kg) to avoid precipitating acute withdrawal while still reversing life-threatening respiratory depression 1
• This more conservative approach maintains some analgesia while restoring adequate ventilation 1

Titration and Repeat Dosing

The key principle is titrating to effect—restoring adequate ventilation—not complete reversal of all opioid effects 1:

• Repeat naloxone every 2-5 minutes as needed if respiratory depression persists 1
• The goal is to restore and maintain a patent airway and adequate ventilation, not to eliminate all opioid effects or provoke severe withdrawal 1
• Doses may need escalation up to 2 mg IV/IM if initial response is inadequate 1

Critical Monitoring Considerations

Patients require continuous observation for at least 2 hours after the last naloxone dose because morphine's duration of action outlasts naloxone's antagonist effect 1, 2:

• Naloxone has a shorter half-life than morphine, creating risk of re-sedation and recurrent respiratory depression 2
• Repeated doses or continuous infusion may be necessary for sustained reversal 2
• Monitor vital signs, oxygen saturation, and respiratory rate continuously 1

Route-Specific Dosing

Intravenous/Intramuscular (Preferred)

• 0.4-2.0 mg IV for adults with severe overdose 1
• 0.1 mg/kg IV/IM for pediatric patients 1

Intranasal

• 2 mg IN, repeated in 3-5 minutes if necessary 1
• This route is increasingly used in community settings and by first responders 1

Important Caveats

Do not administer naloxone to neonates whose mothers have chronic opioid use, as this can precipitate severe withdrawal and seizures 1:

• In opioid-dependent patients of any age, naloxone may induce acute withdrawal syndrome with hypertension, tachycardia, vomiting, and agitation 1
• These withdrawal symptoms are rarely life-threatening but can be distressing 1
• Using the lowest effective dose minimizes withdrawal severity while maintaining reversal of life-threatening effects 1

Hypotension may occur, especially in volume-depleted patients or those receiving concurrent vasodilators 1:

• This usually responds to supine positioning, IV fluids, or atropine if accompanied by bradycardia 1
• Pressors or additional naloxone are rarely needed 1

Continuous Infusion for Prolonged Overdose

For cases requiring repeated boluses or when dealing with long-acting opioid formulations, continuous naloxone infusion is more effective than repeated boluses 2:

• This maintains sustained reversal without the peaks and troughs of intermittent dosing 2
• Particularly important given morphine's longer duration compared to naloxone 3, 2